1. Field
The present disclosure generally relates to processing composite parts, and deals more particularly with a method of curing composite parts that are hollow or have a cavity therein.
2. Background
Composite parts that are hollow or contain cavities/recesses may be cured using a combination of heat and pressure in an autoclave. In order to react autoclave pressure and prevent collapse of the part, a mandrel-like tool such as an inflatable bladder wrapped in a single-layer release film is placed in the cavity. Following curing of the part, the bladder is deflated to allow it to be removed from the part. The bladders used in this application are typically made of air impermeable, flexible materials such as elastomers which may degrade over time because of the elevated temperatures to which they are subjected during thermal cure processes.
In other applications, air impermeable vacuum bags with release films have been fitted inside the cavity without a supporting mandrel, however this approach may not provide adequate structure for reacting applied compaction forces. In still other applications, oversized tube type bags have been fitted over internal mandrels, however this solution to the problem may result in unacceptable results because the oversize bags wrinkle and leave mark-off.
Accordingly, there is a need for a method of curing composite parts that are hollow/contain cavities, which eliminates the need for a mandrel providing internal structural support to react applied compaction forces. There is also a need for a film tube that can be installed in a part cavity that functions as a sealed inner vacuum bag that applies autoclave compaction force to the part.